Mistress repower #2 begins....
02-08-2016, 07:33 AM
#891
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You guys are arguing about a cams ramp slope which determines the acceleration at a given speed. Listed cam specs don't tell the story that well. It would be nice to have actually graphs.
MMB, the only way I can see a spring change gaining 60hp, is if it let the valve events change significantly. That isn't necessarily a good thing for durability if it's due to lofting or something like that.
MMB, the only way I can see a spring change gaining 60hp, is if it let the valve events change significantly. That isn't necessarily a good thing for durability if it's due to lofting or something like that.
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02-08-2016, 07:37 AM
#893
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You guys are arguing about a cams ramp slope which determines the acceleration at a given speed. Listed cam specs don't tell the story that well. It would be nice to have actually graphs.
MMB, the only way I can see a spring change gaining 60hp, is if it let the valve events change significantly. That isn't necessarily a good thing for durability if it's due to lofting or something like that.
MMB, the only way I can see a spring change gaining 60hp, is if it let the valve events change significantly. That isn't necessarily a good thing for durability if it's due to lofting or something like that.
02-08-2016, 07:56 AM
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02-08-2016, 08:02 AM
#896
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I have a $100,000 personal education regarding all motor race engines. Cam Spring specs were 360 on the seat and we changed to a 270 seat. Spring Pressure eats HP, spring diameter can limit rpm etc. etc. Wrong coil bind causes spring surge and I can almost promise you if you set coil bind to the spring manufacture spec it is wrong.
You guys are getting way to technical over such a small cam change on a LOW RPM engine. He has Cam Motion cams call Kip and see what he thinks, I bet it's just fine. There is only so much they can do with a lobe down low, there not going to grind him a POS without making work the best it can. I agree it's the wrong cam and his engine is Lazy but I also feel he doest need to spend $3,000 yanking stuff out to make such a small change to the cam.
Who invented his spring spec? Bob likes heavy springs will it work with lighter springs?
If you are comfortable using heavy 1980 spring technology then by all means use it. I know what I am doing.
You guys are getting way to technical over such a small cam change on a LOW RPM engine. He has Cam Motion cams call Kip and see what he thinks, I bet it's just fine. There is only so much they can do with a lobe down low, there not going to grind him a POS without making work the best it can. I agree it's the wrong cam and his engine is Lazy but I also feel he doest need to spend $3,000 yanking stuff out to make such a small change to the cam.
Who invented his spring spec? Bob likes heavy springs will it work with lighter springs?
If you are comfortable using heavy 1980 spring technology then by all means use it. I know what I am doing.
02-08-2016, 08:15 AM
#897
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I have a $100,000 personal education regarding all motor race engines. Cam Spring specs were 360 on the seat and we changed to a 270 seat. Spring Pressure eats HP, spring diameter can limit rpm etc. etc. Wrong coil bind causes spring surge and I can almost promise you if you set coil bind to the spring manufacture spec it is wrong.
You guys are getting way to technical over such a small cam change on a LOW RPM engine. He has Cam Motion cams call Kip and see what he thinks, I bet it's just fine. There is only so much they can do with a lobe down low, there not going to grind him a POS without making work the best it can. I agree it's the wrong cam and his engine is Lazy but I also feel he doest need to spend $3,000 yanking stuff out to make such a small change to the cam.
Who invented his spring spec? Bob likes heavy springs will it work with lighter springs?
If you are comfortable using heavy 1980 spring technology then by all means use it. I know what I am doing.
You guys are getting way to technical over such a small cam change on a LOW RPM engine. He has Cam Motion cams call Kip and see what he thinks, I bet it's just fine. There is only so much they can do with a lobe down low, there not going to grind him a POS without making work the best it can. I agree it's the wrong cam and his engine is Lazy but I also feel he doest need to spend $3,000 yanking stuff out to make such a small change to the cam.
Who invented his spring spec? Bob likes heavy springs will it work with lighter springs?
If you are comfortable using heavy 1980 spring technology then by all means use it. I know what I am doing.
You had bob spec and design your cams in your engines didnt you?
02-08-2016, 08:31 AM
#898
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Bob's cams come from Cam Motion. Yes Bob had my cams cut, he told me what he wanted to do and I told him what I wanted to happen. My cams have less duration and less lift then he wanted to put in it. I also used springs that were tons lighter than he wanted. and spec'ed my own PAC Racing Valve train parts.
Bob surprised me by switching to LS firing order to smooth out harmonics. It was a well engineered package from both our ideas!!
Anything Else?
Bob surprised me by switching to LS firing order to smooth out harmonics. It was a well engineered package from both our ideas!!
Anything Else?
02-08-2016, 08:53 AM
#900
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I surely dont feel comfortable telling him to keep it, based solely off .050 numbers and lift number. Besides the fact i have seen the carnage from those cams like his, as well as thier power number be down compared to a shelf cam with less lift.
It will be interesting to see how the dyno session goes. A crane 630 lift hyd roller like the 741, 651, call for 150 closed, 450 open, with valve float at 6800, and a max recommened rpm of 6400 with that combo. But, they arent very intense lobes.
An engine builder recently got an invite to do some spintron testing on some marine bbc packages. Might be some interesting data to be found . Maybe tims package can be tried out.
Tim, what was the recommmended spring pressure from bob on your cam ?
It will be interesting to see how the dyno session goes. A crane 630 lift hyd roller like the 741, 651, call for 150 closed, 450 open, with valve float at 6800, and a max recommened rpm of 6400 with that combo. But, they arent very intense lobes.
An engine builder recently got an invite to do some spintron testing on some marine bbc packages. Might be some interesting data to be found . Maybe tims package can be tried out.
Tim, what was the recommmended spring pressure from bob on your cam ?
